The only way your brain can multitask is :1. If one of the tasks you have learned to do so well that it is automatic 2. the tasks involve different parts of the brain (reading while listening to classical music because they use 2 different parts (music with lyrics would be using the language centers along with reading, and that's why you can't do both at the same time)).

What most people think multitasking is is actually serial tasking, or switching between 2 activities in rapid succession. This actually makes your efficiency go down, making it take longer to do 2 things at once than doing both of them separately.

I hope this helps, if you have any questions, feel free to ask!

“Nobody important? Blimey, that’s amazing. You know that in nine hundred years of time and space and I’ve never met anybody who wasn’t important before.” — The Eleventh Doctor